The present invention relates to a cassette formed of a relatively hard material suitable for enclosing a flexible magnetic disk that is rotatable within said cassette, in general, and to simplified means for enhancing the cleaning of, and for stabilizing the motion of, said flexible disk as it is rotated within said cassette, in particular.
Flexible or floppy magnetic disks are widely used as recording media for computers because of their ease of handling and their relatively low cost. A floppy disk is a flexible disk of polyester resin that is coated on one or both sides with magnetic materials on which digital information can be stored or from which such information can be retrieved by a magnetic head as a portion of the flexible disk is rotated past the magnetic head at a relatively high rate of speed in contact therewith or in relatively close proximity thereto.
Floppy disks are usually contained in a flexible jacket formed with a generally rectangular opening that serves as a magnetic head access window and with a center opening for engagement of the disk with a disk drive. In such an arrangement, it is possible for dust or foreign matter to enter the flexible jacket through these openings and to be deposited on the recording medium. On recording media disks with high information density, dust or foreign matter may cause a brief separation of the magnetic head from the recording media and an attendant loss of data from said recording media, a phenomenon that is also referred to as dropout. Also, there is currently a trend toward making a recording media smaller in size (i.e., 31/2 inch diameter disks as opposed to 51/4 and 8 inch diameter disks currently in widespread use). These smaller disks (sometimes referred to as micro-disks) have the advantage that they are very easily transported, even in a shirt or coat pocket. However, this advantage may well lead to increased exposure to dropout producing contaminants.
There are existing designs that provide a measure of contaminant protection to these smaller diameter micro-disks. In general, these designs provide a case or enclosure which is more rigid or durable than the traditional floppy disk jacket. In addition, a shutter is provided to keep dust and foreign matter from entering the case through the magnetic head access window. Like the soft jacketed floppy disks, these newer hard jacketed micro-disks usually include wiping fabrics or cleaning sheets often made of non-woven material that are adhered to the inside of both halves of the jacket or cartridge to wipe any debris from the floppy disk as it is rotated by the disk drive. These sheets also prevent abrading or wearing of the floppy disk by inside surfaces of the hard floppy disk enclosure.
In one previous design, described in U.S. Pat. No. 4,510,546 to ASAMI ET AL, a flexible spring-force member or lifter is provided on an inside surface of the hard disk-enclosing case that presses a portion of a cleaning sheet against a surface of the floppy disk to thereby enhance the cleaning action of each of said cleaning sheets. The spring-force member is adhesively attached to said inside surface and a radially extending rib molded on the same inside surface cooperates with said spring-force member to provide the required cleaning-action-enhancing spring-force. Disadvantages associated with a spring-force providing member of this type include the necessity of providing an additional piece-part for the magnetic disk cassette (the flexible spring-force member), the difficulty of consistently fabricating a spring member of this type that will provide the same desired spring force level when installed in each cassette, and the normal change in the magnitude of the spring-force provided by a lifter or spring-force member, fabricated from materials such as synthetic resins, that naturally occurs as a result of the aging process.
It is a primary object of the present invention, therefore, to provide spring-force means for enhancing the cleaning function of a liner located within a magnetic disk cassette that will require no additional cassette piece-parts.
It is another object of the present invention to provide spring-force means for enhancing the leaning function of a disk-cleaning liner included within a magnetic disk cassette that will readily and consistently provide the desired spring-force level at the time that a magnetic disk cassette is being manufactured.
It is another object of the present invention to provide spring-force means for enhancing the cleaning function of a disk cleaning liner included within a magnetic disk cassette that will provide a consistent spring force level over an extended period of time.
It is yet another object of the present invention to provide spring-force means for a magnetic disk cassette that will stabilize magnetic disk movement lateral to the direction of disk rotation in the region where the magnetic head and the rotating disk magnetically interact with one another.
It is a further object of the present invention to provide spring-force means for a magnetic disk cassette that is capable of laterally positioning the magnetic disk to a predetermined location in the region near the magnetic head, while the magnetic disk is being rotated.